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0 pointsMauranKilom4y ago0 comments

It's worse actually. The MSVC STL uses 16 byte (or however large your element is, if greater) chunks. Source:

https://github.com/microsoft/STL/blob/main/stl/inc/deque#L56...

They have made clear that this won't be changed, for ABI stability reasons.

That makes std::dequeue basically unusable in a portable context. In virtually any situation, "allocate each element separately" and "allocate elements in 4k chunks" are on opposite ends of the performance spectrum.

0 comments

brandmeyer4y ago

That is quite unfortunate, and I freely admit that I'm unfamiliar with MSVC's current quirks.

> They have made clear that this won't be changed, for ABI stability reasons.

Also unfortunate. Once upon a time, users had to be extra careful to control which version of the runtime DLL their program transitively linked to since MS would issue a new ABI-breaking version with every major compiler release. Sounds like they got ABI stability religion just in time to lock in some unfortunate decisions.

beached_whale4y ago

Thanks, I remembered incorrectly.

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